Mechanical and Process Properties of Welded Round Steel Pipes for Structures from Fine Grained Structural Steel According to DIN 17123-1986
Abstract
This article identifies the mechanical and process properties of welded round steel pipes for structures from fine-grained structural steel according to DIN 17123-1986. This document provides basic information about the steel pipe material, its valid diameter range, its wall thickness, strength properties and mechanical properties, as well as other information. The solutions proposed in this document provide practical guidance and technical reassurance to engineers in their engineering projects.
Introduction
Steel pipes are tubular products manufactured from specified steel, which can be divided into seamless (round) steel pipes, welded round steel pipes, elliptical steel pipes and other shapes. Steel pipes are widely used in water conservancy projects, oil wells, gas transmission and other fields. They are also indispensable in the production and storage of oil and gas pipelines and pressure vessels. DIN 17123-1986 is a steel pipe for welding structures with fine grained structural steel.
Material
According to DIN 17123-1986, the steel grade available for welded round steel pipes for structures from fine grained structural steel is nominal grade St 37-2U, -2N, and St 44-2U, St 44-2N and St 52-3U, and St 52-3N; the chemical composition should comply with the provisions of table 1.
Table 1 Chemical composition of steel grade
Grade Steel grade C SI Mn S P
St 37-2U 0.17 0.35 0.40-1.20 ≤0.035 ≤0.035
St 37-2N 0.17 0.35 0.40-1.40 ≤0.035 ≤0.035
St 44-2U 0.21 0.35 0.40-1.20 ≤0.042 ≤0.042
St 44-2N 0.21 0.35 0.40-1.4 ≤0.042 ≤0.042
St 52-3U 0.25 0.50 0.55-1.20 ≤0.034 ≤0.034
St 52-3N 0.25 0.50 0.55-1.4 ≤0.034 ≤0.034
Diameter and wall thickness
The wall thickness of the steelpipe should comply with the requirements of table 2. The diameter of the steel pipe should conform to the provisions of DIN 17123-1986.
Table 2 Wall thickness of steel pipe
Thickness grade Wall thickness mm
T1 0.8
T2 1.0
T3 1.2
T4 1.5
T5 1.8
T6 2.0
Strength Properties
The strength properties of steel pipes with nominal diameter ranging from 32 mm to 150 mm should comply with the provisions of table 3.
Table 3 Strength properties
diameter 0/d Mpa d0/t Mpa
32-150 ≥410 ≥5.5
Workmanship
When welding structures with fine grained structural steel according to DIN 17123-1986, welders must have a valid certificate and comply with the requirements of the relevant welding technology. If a steel pipe is directly welded to the base material, the surface defect of the base material directly adjacent to the welded steel pipe shall not exceed the wall thickness of the steel pipe.
Testing
The welded steel pipes for structures from fine grained structural steel should be inspected and tested according to the provisions of DIN 17123-1986. The inspection items and methods should be confirmed before the test. The samples needed to be tested should be determined based on the actual situation.
Conclusion
In conclusion, this article discussed the basic information concerning the welded round steel pipes for structures from fine grained structural steel that conforms to DIN 17123-1986. This document provides basic information about the steel pipe material, its valid diameter range, its wall thickness, strength properties and mechanical properties, as well as other information. The solutions proposed in this document provide practical guidance and technical reassurance to engineers in their engineering projects.
